Done some very quick, light labwork. About 15 minutes worth. Please double check:
D2:
It still says 15 frames but I think they just didn't update it. It feels too different
Batman: D2 is not worth it, much easier to air-to-air him. You can if you want to, but the weird hurtbox on Joker means he can stuff you at angles you would normally win. Spacing dependent. The further he is in front of you, the easier it will be. The closer they are, you're taking more of a risk to do it on reaction.
Doomsday/Bane: Splashes are free now, late or early, near or far. They can push J. D3 at the peak of their jump and you'll still get them because of how high above Joker's hurtbox the crowbar hitbox is. I was surprised at how easy these were to AA compared to Batman's j.2
Scorpion: J3 is still great air to air, but even deep J3's are total ass against grounded Joker and will get stuffed by even late D2's. Scorpion's j.3 has been nerfed to utter shit (HI
Cat !!!!!

)
Parry and HAs:
Substantially better. You will see it visually. When you hit parry late, you'll actually see the last frame or two of animation for parry before it hits. For a second, you'll think you whiffed but then parry connects. Timing is lenient. B3 and F3s should be free to anyone with a modicum of reaction time. You see the windup? Push parry.
3 HAs last a stupid amount of time. It feels like forever. Acceleration in walkspeed might have changed. Combos change because of the jump arc. The 47% bnb is easy but also different with the timing. The new D2 also helps regardless of HA level. This should be the go-to combo now.
I can see how parry will become part of his meta game and matchups. Timing your parry with little tricks becomes viable because you can afford to be off by several frames, so they can become easy guidelines. Example: Against' Flash's crusher f2,1, whiff d.1, press parry. Not strict at all. For Killer Frost/Batman I see something like 212, gun dash cancel, press low parry becoming safe setups to catch wakeup moves and ultimately shut them down. Parry setups are more viable now.
PS: GL's B1, 2 feels impossible to parry, at least to me. Just frame, I'm sure of it. B1, 3 however is easy as hell and there is a wide window where you can parry B1,3 and continue blocking for B1,2 so just use that timing.